Electrothermal device.



No. 830,391. PATENTED SEPT. 4, 1906l C. E. WHHE.

BLECTROTHERMAL DEVICE.

APPLIGATION' FILED JUNE 22.1903.

1n: Norms PErsRs ca., WASHINGTON, n. c.

PATIENT OFFICE.,

CHARLES E. VHITE, OF CHICAGO,

ILLINOIS, ASSIGNOR 'IO FRANK B.

COOK, OF CHICAGO, ILLINOIS.

ELECTROTHERIVIAL DEVICE.

Specification of Letters Patent.

Patented Sept. 4, 1906.

Application filed June 22,1903. ScrialNo.162,469.

To all 'wl/mm t may concern,.-

Be it known that I, CHARLES E. VVrn'rn, a citizen of the United States of America, and a resident of Chicago, Cook county, Illinois, have invented a certain new and useful Improvement in Electrothermal Devices, of which the following is a specification.

My invention contemplates an improved electrothermal device consisting of a high-resistance or heat-concentrating member and an expansible medium and means whereby the expansion of said medium is capable of producing the desired result.

As herein shown and described, my invention is embodied in a heat-coil for protecting electrical apparatus against the intrusion of abnormally strong currents. For this particular purpose my invention, as herein descrilwd and illustrated, preferably comprises a hcrmetically-sealed chamber' containing a heat-coil or other heat-concent 1ating member. A shifting medium, such as a body of mercury or a thin llexible diaphragm, is arranged to be subject to the pressure of the air in said chamber when the same is expanded by the heat resulting from the passage of an. abnormally strong current through the said heat-coil or he:it-concentrating member. The said diaphragm or mercury is included in the imam circuit and is adapted when shifted slightly by the expanding air to open the said circuit. Also, if desired, the said diaphragm or mercury can be arranged to close a connection to ground at the same time that it opens the main circuit. Preferably the internallyarranged switch-contacts are combined with a confined body of air adapted to counteract the effects of atmospheric changes of temp eraturc on vthe body of air which is employed Vfor shifting the diaphragm or mercury. In other words, the switch-contacts, tl e air or other Iluid, and. the diaphragm or mercury, as the case may be, can all be advantageously inclosed or sealed up in the same inclosure. If a diaphragm is employed, a confined body of airis arranged at cach side of such diaphragm. With this provision. atmospheric changes of temperature have no tendency to alter the normal condition of the device. The same is true, of course, with the provision of a coun- Aterb al ancin g medium lin connection with mercury.

The nature and advantages of my invention will, however, hereinafter more 'fully appear.

In the accompanying drawings, Figure l is a longitudinal section through a heat-coil or thermal protector embodying the broad idea of my invention. showing a slightly different construction.. Fig. 3 is a sectional view of a thermal protector involving the use of mercury instead. of a diaphragm.

Referring to F ig. 1, my improved heat-coil, or thermal protector, as they are sometimes called, comprises a metallic cylinder A, provided at its ends with air-tight rubber ca ps B and B. At a point preferably midway between its ends the interior of the said cylinder is divided into two compartments by a flexible metallic diaphragm C. The cap B carries a contact Z1, adapted to normally make contact with the metallic diaphragm C. A metallic contact b is mounted on the cap B/ and arranged. ust out of contact with the said diaphragm. A binding-post b2 on the cap B is connected with the contact by means of a heat-coil or coil of high resistance l). A binding-post b3, mounted on the cap B, is electrically connected with the Contact Il. Another binding-post a, mounted on the metallic cylinder A, is electrically connected with the diaphragm C. rlhus the said coil or heatconcentrating member D is arranged in a hermctically-sealed chamber E, and this chamber is separated from a similar chamber '.F by means of the springy or Vflexible metallic diaphragm C.

In use the line-wire can be connected with the binding-post c, while the switchboard connection, or connection leading to the instruments to be protected, can be connected with the binding-post b2. The ground conductor can be connected with the bindingpost b3. FVith this arrangement all currents traversing the main circuit will pass through the diaphragm C and the heat-coil D, the two being connected in serios in the said circuit. In ease an abnormally strong current should show its presence in the circuit the heat generatcd by such current while passing through the coil D will be su'llieient to expand the air contained in the chamber E and to thereby subject the diaphragm C to pressure. A very Fig. 2 is a similar view IOO tiki. 830,391

slight degree ot pressure will be s'uiticient to cause the said diaphragm to move out oi contact with the projection or contact-piece i) and into contact with the other contact-piece b. Thus the flexing of the diaphragm under the air-pressure serves to both open the liliecircuit and to connect the line with ground. In this way the instruments or apparatus to be protected are cut ott from the circuit, and the trespassing current is attorded a path to ground.

Vith the provision of a chamber at each side ot the diaphragm C it will be observed that changes in temperature of the surrounding atmosphere will have no etiect whatever upon the said diaphragm, the two chambers tending always to equalize the pressure at opposite sides ot the diaphragm.

In Fig. 2 the construction is substantially the same as that shown in Fig. 1 with the exception that a heat-coil G is arranged upon the outside of the casing rather than within the same, and with the further exception that an insulated binding-post g is provided for completing the connection between the said heat-coil and the switchboard-wire. An abnormally strong current in passing through this coil G, which is preferably of insulated German-silver wire, will heat the chamber ll at one side ot the diaphragm I, thereby causing the latter to move out ot contact with the contact-piece 7iy and into contact with the projection or contact-piece i. ln this way the line-circuit is broken and the connection to ground is completed, the operation being the same as that already described in connection with Fig. 1, and the two constructions, as stated, being substantiallyv the same, except that in Fig. 1 the coil is inside ot the casing, while in Fig. 2 the said coil is wrapped around the outside otl the casing.

ln Fig. 3 the construction involves a U- shaped tubular casing J, preferably of glass, and containing a sullicient quantity of mercury K. One leg of the said casing contains a heat-coil L, which can be connected with the switchboard and which is provided with a downwardly-extending contact l, the latter j ust entering the surface ot the mercury. The other leg of the casing is provided with a contact j, normally just touching the surface ot the mercury and adapted at its upper end to be connected with the line-wire. Another contact j, normally just out ot engagement with the surface ot the mercury, is adapted to be connected with a ground conductor. lVith this arrangement all currents traversing the line-circuit will pass through the wire l or contact y', thence through the mercury, through the contact l, and, finally, through the heat-coil Lto the switchboard conductor, Consequently should an abnormallyT strong current be developed in the circuit the heat generated by the coil L will expand the surrounding body ot air contained in the glass e third contact-piece y.

casing, and thereby causer the body ot mercury to shift out ot Contact with the wire or contact-piece Z and into contact with the This, as in the other constructions, serves to close or open the line-circuit and simultaneously therewith connect the line with ground. Changes in atmospheric temperature will not cause a bodily shift ot the mercury one way or the other, inasmuch as this construction, like the other two, involves a couple of equalizingchambers M and N, similar to the chambers E and F of the construction shown in Fig. 1.

My improved electrothermal device is not only very sensitive and responsive to currents only slightly in excess ot normal, but is also ot a self-restoring character-that is to say, it is capable ot restoring the circuit to its normal condition upon the cessation o'l abnorinai current-iil used as a thermal protector 'for protecting electrical circuits and apparatus.

lit will be observed that the broad idea ot my invention is ada ptcd tor various purposes and is not necessarily limited to heat-coils or thermal protectors. For example, av heatconcentrating member, a body oi expansible iluid, and means resjionsive to the expansion ot said 'fluid can be employed in various connections-such as relays, circuit closing or opening devices adapted to be controlled at will, and othe" similar devices. .figaiin a. heat-concentrating member and an expansible medium can be employed as 'the essential elements ot instruments 'lor measuring electrical currents. Bi'oadly considered, my invention contemplates an improved elecrothermal device tor any and all purposes lor which it may be tound useful.

In each case it will be seen that I provide a hermetic; lly-sealcd chamber containing normally closed contacts. in Figs. 1 and 2 the center ot the diaphragm serves as one contact, while in Fig. 3 the surtacc ot the body ot mercury is one Vot the contacts. lt will be readily seen that the diaphragm need not necessarily be constructed entirely ot conducting material and that various modifications may be adopted without departing trom the spirit o'l'l my invention. 'lhus it will be seen that 1 provide an rimproved construction involving an advain ageous combining ot couiiterbalancing-chambcrs or bodies ot air with internally-arrange(l switch-cont acts, the same all being preferably inclosed or sealed up together in the saine inclosure. Also it will be seen that it employ the lieature oi a chamber divided into two counterbalancingcompartments or bodies ot air by a llexible diaphragm. Moreover. my improved arrangement coinbines the features ot internally-arranged contacts and a llcxible circuit opening and closing diaplnagm, together with a suitable resistance 'l'or generating the heat necessary tor actuating the diaphragm.

IOCy

IlO

l hat claim as my invention is y l. An electrothermal device for use in protecting electrical apparatus against abnormally strong currents, comprising a flexible metallic diaphragm, a coniined body of air adapted to act on said diaphragm, a switchcontac-t engaging said,diaphragm, a heatconcentrating member' for heating said body of air, and means for connecting said diaphragm, contact and heat-concentrating member in series in a circuit.

2. An electrothermal device for use in protecting electrical apparatus against abnormally strong currents, comprising a shifting conducting medium, a confined body et iiuid adapted to act on one side of said shifting medium, another confined body of iluid adapted to act on the other side ot said shifting medium, a contact normally engaging said shifting medium, a heat-concentrating member associated with one of said con'lined bodies et fluid, means for connecting said heat-concentrating member, contact and shifting conducting medium in series in a circuit7 and a ground connection having a contact adapted to engage said shitting coi'iducting medium upon the passage of an abnormal current through said heat-concentrating member, and upon thc consequent expansion of the body of iiluid associated with said member.

3. An electrothermal switch comprising a Atlexilile metallic diaphragm, a confined body ot air adapted to act on one side of said diapliragm, a confined body ot air at the other side of said diaphragm, a contact normally engaging said diaphragm, a heat-concentrating member for heating said first-mentioned body oit air, and means for connecting said diaphragm, contact and heat-concentrating .member in series in a circuit.

4t. An electrothermal switch comprising a 'flexible metallic diaphragima coniined body ot air adapted to act on one side ol' said diaphragm, a Contact inclosed in said body oi air and normally engaging said diaphragm, a heat-concentrating member for heating said body of air, and means for connecting` said ascesi diaphragm, contact and heatconcentrating member in series in a circuit.

5. .An electrothermal switch comprising a flexible metallic diaphragm, a metal tube having its interior divided transversely into two compartments by said diaphragm, means for closing the ends of said tube, so as to provide a coniined body of air at each side of said diaphragm, an insulated contact normally en gaging said diaphragm, a high resistance 'for heating the air at one side of the diaphragm, and means 'for connecting said diaphragm, contact and high resistance in series in a circuit.

6. An electrothermal switch comprising a metal tube, a metallic diaphragm dividing the interior of said tube transversely into two compartments, means for sealing the ends of said tube, so as to provide a confined body of air at each side of said diaphragm, insulated contacts mounted at either side of said diaphragm, one of said contacts normally engaging the diaphragm, the other contact being normally out of engagement with the diaphragm, a high resistance wound at or near the part of the tube which incloses the contact normally in engagement with the dia* phragm, and means for connecting said diaphragm, normally engaging contact and high resistance in series in a circuit.

7. An electrothermal switch comprising a metallic casing, a 'flexible diaphragm dividing the interior of saidcasing into two compartments, insulated contacts suitably mounted at opposite sides of said diaphragm those at one side being normally closed., a high resistance wound at or near and associated with the compartment rcontaining the normally closed contacts, and means 'for connecting said normally closed contacts in series in a circuit.

Signed by me at Chicago, Illinois, this 19th day oi' June, 1903.

CHARLES E. VVHITF.

/Vitnesses CHAs. HIoKoK, WM. A. HARDERS. 

